Metal gasket

Abstract

A metal gasket 10 includes a pair of bead plates 14 and 14 having a cylinder hole 12 corresponding to a cylinder bore, a full bead 22 surrounding the cylinder hole, a first intermediate plate 18 interposed between the pair of bead plates, and a shim plate 16 interposed between the first intermediate plate and one bead plate in an area around the cylinder hole. The shim plate 16 is disposed to overlap with the full bead 22 , and the thickness of a contact portion 19 to contact with the shim plate 16 of the first intermediate plate changes in the peripheral direction of the cylinder hole.

The invention claimed is: 
     
       1. A metal gasket interposed between joint surfaces of a cylinder block and a cylinder head to fasten said cylinder block to said cylinder head by a fastening bolt so as to seal the joint surfaces, characterized by comprising:
 a first bead plate having a first cylinder hole corresponding to a cylinder bore and a first full bead surrounding the first cylinder hole; 
 a second bead plate having a second cylinder hole corresponding to the cylinder bore and a second full bead surrounding the second cylinder hole; 
 a first intermediate plate interposed between the first and second bead plates; and 
 a shim plate interposed between the first intermediate plate and one of the first and second bead plates in an area around its cylinder hole; 
 wherein said shim plate is disposed to overlap with said first and second full beads, a plate thickness of a contact portion of said first intermediate plate contacting said shim plate varies in the circumferential direction of the cylinder hole, the plate thickness of said contact portion is thicker at a position away from the bolt hole than at a position adjacent to the bolt hole and the plate thickness in a cylinder axis direction of the contact portion varies in the circumferential direction of the cylinder hole and a first side of the first intermediate plate is a planar surface and the thickness of the first intermediate plate varies by means of a depression on an opposite side thereof. 
 
     
     
       2. The metal gasket according to  claim 1 , characterized in that a second intermediate plate is provided at an opposite side of the shim plate to the first intermediate plate by sandwiching said shim plate and said shim plate is fixed to the second intermediate plate. 
     
     
       3. The metal gasket according to  claim 1 , characterized in that said shim plate is fixed to the second intermediate plate by welding and the welding position is located in said first and second full beads. 
     
     
       4. The metal gasket according to  claim 1 , characterized in that a third bead plate having a third full bead projecting in a direction opposite to one of said first and second full beads at a position overlapping the first and second full beads is interposed between said first intermediate plate and the bead plate having said one of the first and second full beads. 
     
     
       5. The metal gasket according to  claim 1 , characterized in that a third bead plate having a third full bead projecting in a direction opposite to one of said first and second full beads at a position overlapping the first and second full beads is interposed between said second intermediate plate and the bead plate having said one of the first and second full beads. 
     
     
       6. The metal gasket according to  claim 1 , characterized in that a third bead plate having a third full bead projecting in a direction opposite to one of said first and second full beads at a position overlapping the first and second full beads is interposed between said second intermediate plate and the bead plate having said one of the first and second full beads and a fourth bead plate having a fourth bead projecting in a direction opposite to the other of said one of said first and second full beads at a position overlapping the first, second and third full beads is interposed between said first intermediate plate and the bead plate having the other of said one of said first and second full beads. 
     
     
       7. The metal gasket according to  claim 1 , characterized in that a dimensional difference between a position with a large plate thickness and a position with a small plate thickness in the contact portion of the first intermediate plate is 5 to 50 μm. 
     
     
       8. A metal gasket interposed between joint surfaces of a cylinder block and a cylinder head to fasten said cylinder block to said cylinder head by a fastening bolt so as to seal the joint surfaces, characterized by comprising:
 a first bead plate having a first cylinder hole corresponding to a cylinder bore and a first full bead surrounding the first cylinder hole; 
 a second bead plate having a second cylinder hole corresponding to the cylinder bore and a second full bead surrounding the second cylinder hole; 
 a first intermediate plate interposed between the first and second bead plates; and 
 a shim plate interposed between the first intermediate plate and one of the first and second bead plates in an area around its cylinder hole; 
 wherein said shim plate is disposed to overlap with said first and second full beads, a plate thickness of a contact portion of said first intermediate plate contacting said shim plate varies in the circumferential direction of the cylinder hole, the plate thickness of said contact portion is thicker at a position sandwiched by an adjacent cylinder hole than at another position and the plate thickness in a cylinder axis direction of the contact portion varies in the circumferential direction of the cylinder hole and a first side of the first intermediate plate is a planar surface and the thickness of the first intermediate plate varies by means of a depression on an opposite side thereof. 
 
     
     
       9. The metal gasket according to  claim 8 , characterized in that a second intermediate plate is provided at an opposite side of the shim plate to the first intermediate plate by sandwiching said shim plate and said shim plate is fixed to the second intermediate plate. 
     
     
       10. The metal gasket according to  claim 8 , characterized in that said shim plate is fixed to the second intermediate plate by welding and the welding position is located in said first and second full beads. 
     
     
       11. The metal gasket according to  claim 8 , characterized in that a third bead plate having a third full bead projecting in a direction opposite to one of said first and second full beads at a position overlapping the first and second full beads is interposed between said first intermediate plate and the bead plate having said one of the first and second full beads. 
     
     
       12. The metal gasket according to  claim 8 , characterized in that a third bead plate having a third full bead projecting in a direction opposite to one of said first and second full beads at a position overlapping the first and second full beads is interposed between said second intermediate plate and the bead plate having said one of the first and second full beads. 
     
     
       13. The metal gasket according to  claim 8 , characterized in that a third bead plate having a third full bead projecting in a direction opposite to one of said first and second full beads at a position overlapping the first and second full beads is interposed between said second intermediate plate and the bead plate having said one of the first and second full beads and a fourth bead plate having a fourth bead projecting in a direction opposite to the other of said one of said first and second full beads at a position overlapping the first, second and third full beads is interposed between said first intermediate plate and the bead plate having the other of said one of said first and second full beads. 
     
     
       14. The metal gasket according to  claim 8 , characterized in that a dimensional difference between a position with a large plate thickness and a position with a small plate thickness in the contact portion of the first intermediate plate is 5 to 50 μm.